Hormones

Free testosterone

Free T

Included in Baseline and Complete.

Estimating the testosterone your tissues can readily use.

Most testosterone in your blood is bound to proteins. Free testosterone is the small unbound portion that can readily reach your cells, so it adds useful detail when total testosterone or SHBG results are hard to interpret.

Total testosterone doesn't always tell the whole story.

SHBG, a protein made mainly by the liver, holds testosterone tightly. When SHBG runs high or low, which can happen with aging, excess weight, diabetes, thyroid conditions, or some medications, total testosterone may not reflect what your tissues receive. Free testosterone helps fill that gap for both men and women.

Labs produce this result in different ways. Some calculate it from total testosterone, SHBG, and albumin, and others measure it directly. Guidelines favour calculated results or a specialized method called equilibrium dialysis over quick direct tests. Comparisons over time are most reliable within the same lab.

Total testosterone counts it all. Free testosterone shows what's available.

Questions

Is free testosterone useful for women?

Yes. Women have much lower testosterone than men, and the 2023 international PCOS guideline lists calculated free testosterone among the preferred ways to check for higher androgen levels. It's often reviewed when there are symptoms such as excess hair growth, acne, or irregular periods.

Does the time of my blood draw matter?

Yes. Testosterone is highest in the morning, so guidelines recommend a morning draw, ideally early in the menstrual cycle for women who have periods. A repeat test is common before drawing conclusions. Biotin supplements can interfere with some hormone tests, so mention them to your clinician.

How do I make sense of my result?

Free testosterone is read alongside total testosterone, SHBG, symptoms, and medications. In the MyHealthspan app, an AI health assistant can help explain how these results fit together, and a clinician can advise whether repeat or further testing is worthwhile.

Sources and references